Sound reproducing apparatus



- Oct, 31, 1939. R. E. BOWLEY 2,178,030

SOUND REPRODUCING APPARATUS Filed June 9, 1931 m 3 F j 2 22 /8 i 7 /7 f 26 M I. i as l7 0 5 v y v\ I 2 Z I I INVENTOR'K Patented Oct. 31, 1939 om'reosmrss .sArENT OF-Fi CE SOUND REPRODUCING APPARATUS Raymond E. B'owley, San Anselmo, Calif. Application June 9, 1937, Serial No. 147,278

1 Claim.

This invention relates to sound reproducing apparatus. employing a moving actuating coil type diaphragm and actuating means of electrodynamic construction or similar actuating means,

such as loud speakers adapted for use with radio receiving sets, phonograph record turntables with motor and electric pick-up, etc.; telephone devices, microphones and other devices in the class described.

An object of the invention is to provide co-operative shim means in the construction. of a sound reproducing device having a moving actuating coil type diaphragm, such as a loud speaker having electro-magnetic means for actuating the 5 diaphragm over substantially the entire frequency range to which the diaphragm will respond, whereby the response of the diaphragm is caused to be modified efiecting improved resultant tones within the frequency range of the dia- 20 phragm; the said device comprising electro-dynamic means for actuating the diaphragm as d scribed, a moving coil type diaphragm carrying an actuating coil and having a flexible rim, means for mounting the diaphragm and actuating 25 means in operative assembly including means for supporting the rim of the diaphragm in a fixed position.

Other objects of the invention are to provide an improved loud speaker or sound reproducing 30 device in the class described including shim elements adapted for adjusting or regulating the relative operative positions of the fixed position of the periphery of the diaphragm of the device and magnet elements of the device associated 35 with the diaphragm, in either direction, forward or backward, on a plane parallel with the axis of the diaphragm, to compensate for contraction or expansion of the material composing the diaphragm due to atmospheric conditions and other 40 causes during a period of operation while in service, or for other purposes, whereby the response of the diaphragm is caused to be modified efiecting improved resultant tones.

For the sake of explaining the principles of the 45 invention, I will now describe illustrative embodiments thereof. The drawing is for illustrative purposes only and is not drawn to scale. The details of mechanical construction being left to the skill of the experienced workman employing 50 the apparatus herein described and claimed.

In the accompanying drawing:

Fig. 1 is a front View of apparatus embodying the invention.

Fig. 2 is a side view of another modification of 55 the apparatus shown in Fig. 1.

Referring to the drawing:

In Figures 1 and 2 a sound translating device or a loud speaker 3 is shown having a moving actuating coil type diaphragm including a flexible flanged rim 2 composed of soft leather or other 5 flexible material adapted for improving the elasticity of the diaphragm at the rim or periphery thereof; a cylindrical sleeve 5 is attached to the center and rear portion of the diaphragm, an actuating coil 6 is wound upon sleeve 5 for coupling 10 with electro-dynamic or other suitable actuating means i adapted for actuating the diaphragm I over substantially the entire frequency range to which the diaphragm will respond.

A flexible member 9 is applied to the diaphragm i and sleeve 5 and is also attached to the head of the inner pole portion ll of the magnet unit 7; removable screw or bolt 8 is for attaching the flexible member Q to the head of pole portion H by means of an aperture and screw threads 8A provided in the head of pole portion ll; a spacer 0r washer I0 is applied between the head of pole portion I7 and the flexible member 9 for locating coil 5 in the proper position in the air gap l l formed by the magnet poles.

Mounting means l2 forms a mounting device for supporting the diaphragm i and the actuating unit I in operative assembly. Diaphragm i in the modification of the invention illustrated is shown as substantially conical but may take other forms. Annular members l4 and it may be metal or non-metal, composition or any suitable material; an annular member MA may be used for reinforcement when the member id or the member l9 or both said members are composed of non-metal material. The flanged portion 4 of the mounting means is attached to the annular mounting portion MAHi and i9 by rivets, screws, bolts or other suitable means 2|; the mounting portion l2 extends rearwardly toward the center and rear portion of the diaphragm I and includes a portion l8 for supporting the actuating means I in operative assembly with the diaphragm I.

As illustrated in Figs. 1 and 2, the coil and sleeve 5 are flexibly suspended movable in the air gap ll substantially concentric with the air gap and the pole portion i'i. Openings 22a are provided in plate I8 and the mounting portion It for fastening screws or bolts 22 provided for mounting the unit I on the portion l8 of the mounting means l2.

The magnet element of theactuating unit l is an improved adjustable arrangement embodying my invention, comprising the elements described,

a guideway or guideways 29 being provided in the outer pole plate I8 for guiding the magnet portions I6 into supporting position in assembly with plate portion E8 of the magnet; a screw or screws or bolts 2% fasten magnet elements I6 and I8 in operative assembly, portion I5 at the rear of the magnet is part of the connecting portions I6 of the magnet, the portions I5 and [6 of the magnet support the inner pole portion I I of the magnet so that the outer end or head of the inner pole element is projected into the opening in the outer pole plate I8 forming air gap l l.

Shims 21 are provided in the magnet assembly for effecting adjustment of the magnet portion I5-IB whereby pole piece Il may be adjusted in position in either direction parallel with the axis thereof, whereby expansion or contraction of the material composing the diaphragm I or the flexible rim or periphery 2 of the diaphragm may be compensated for by moving the center and rear portion of the diaphragm carrying the sleeve 5 and coil 6 in either direction, forward or backward, the flexible member 9 being attached to the head of the pole piece ll by removable screw 8; the washer or spacer II] at the head of the pole piece I1 is for locating the coil 6 in proper position in the air gap II. By changing the dimensions of the shim means the said adjustment may be made.

Guideways are provided in the mounting portion l8 and in the plate l8 as shown by numeral 26 for centering the magnet poles and air gap substantially concentric with the fixed position of the diaphragm I. The screws or bolts 22b tend to fasten the magnet elements firmly in operative assembly and are adapted for releasing said elements for effecting said adjustment thereof, whereby expansion and contraction of materials composing the apparatus may be compensated for and maximum operating efiiciency maintained over a long period of time; a cavity 383 is provided in plate I8 for the head or" screw or bolt 2222.

This arrangement is simple in construction and provides for rapid assembly of the various ele' ments of the device and also provides for the device to be readily taken apart by an experienced workman without removing the diaphragm from its fixed position of support at the periphery of the diaphragm; the actuating coil, air gap and field coil may be easily examined for cleaning out filings from the air gap or for repairs to the voice coil or to the field coil. Servicing the device is simplified by the arrangement described. The head of the screw or bolt 22?) is concealed between the plate I8 and the mounting portion I8 when the device is in operative assembly with the diaphragm i so that the adjustment is not likely to be tampered with by inexperienced persons. In the modification illustrated and described, the inner pole portion I1 is shown cast with portions I5 and id as a single element so that the head of the inner pole piece is maintained substantially concentric with the opening in the outer pole plate I8 by the guideways 29. I do not confine myself to the particular arrangement or modification herein described to illustrate the principle of the inventive concept.

The embodiments of the invention illustrated and described herein have been selected for the purpose of setting forth the principles involved. The invention is, however, susceptible to being further modified to meet difierent conditions encountered in its use without departure from the inventive concept disclosed.

I realize that other modifications of this invention are possible, therefore I say my invention is not limited to the particular constructions shown and described, and it is my intention to cover all other modifications which can be made without departing from the spirit of the invention or the scope of the claim.

Obviously my invention may be carried out in other ways than herein set forth by way of illustration. I desire it understood that the claim hereunto appended is to be considered in defining my invention rather than the exact disclosures herein made.

My co-pending application for U. S. Letters Patent, Serial No. 226,136, filed August 22, 1938, for Acoustical apparatus is a continuation in part of this application.

My co-pending Application for U. S. letters Patent, Serial No. 247,865, filed December 27, 1938, for Sound reproducing apparatus is a continuation in part of this application.

I claim:

In combination in sound reproducing apparatus, an inner magnet pole piece, a pole plate having a circular opening therein substantially concentric with the pole piece, a magnet portion supporting the inner pole piece and connecting the pole portions of the magnet, means for fastening the magnet elements firmly in assembly, the head of the pole piece projecting into said opening in the plate forming an air gap, a moving coil type diaphragm composed of relatively flexible material having a flexible flanged rim, a cylindrical sleeve attached to the center and rear portion of the diaphragm, a voice coil mounted on the sleeve, the coil and sleeve projecting into the air gap substantially concentric therewith, a flexible member applied to the diaphragm and sleeve and also applied to the head of the inner pole piece for flexibly suspending the sleeve and coil movable in the air gap, removable screw means fastening the flexible member to the head of the pole piece, means provided in the head of the pole piece for receiving said screw, a field coil applied to the inner pole piece and magnet, a mounting structure for the diaphragm and actuating means, the actuating means attached to said structure, the rim of the diaphragm supported in a fixed position, the pole plate forming a support for the magnet, means for fastening the magnet to the mounting structure, removable shim means in the magnet assembly whereby changing the dimensions of said shim means effects a change in the operative position of the inner pole piece in either direction parallel with the longitudinal axis thereof.

RAYMOND E. BOWLEY. 

